How to Get TextEvent in a window of another running process(linux gtk)

I have read a lot of document. But I can't find a little clue. I want get the text event in a window of a running process. I have not the source code of the process,of course. It is like the hook in a microsoft windows. thank for any tips.___

How to Get TextEvent in a window of another running process(linux gtk)

I have read a lot of document. But I can't find a little clue. I want get the text event in a window of a running process. I have not the source code of the process,of course. It is like the hook in a microsoft windows. thank for any tips. ___